The present invention relates to a shutter assembly, and particularly to an improved framing shutter assembly for a luminaire.
Theatrical luminaires can be provided with shutters to provide a projected, framed light beam of a selected shape and size. In typical arrangements, four shutter blades are mounted within the luminaire housing for movement relative to the light path. The blades can be translated radially into and out of the light path and can be rotated in the peripheral direction around of the light beam. By arranging the shutter blades, the projected light beam can be square or rectangular or have other straight sided shapes such as triangular or trapezoidal, and the projected shape can be oriented at a selected rotational position.
In the past, manually operated shutters were common. In a manually operated shutter assembly, handles projecting from the luminaire are manipulated to place the shutter blades in the desired positions. Because of the inconvenience of manual adjustment for each modification in the light beam shape, a need has arisen for a motor operated, automated, remotely controlled shutter assembly.
Existing automated shutter assemblies are subject to disadvantages. Typically, known arrangements are very complex, requiring many intricate parts and assembly operations and resulting in high material and assembly labor costs, large size and poor reliability. Large size is a problem because if a large luminaire housing is needed to contain the shutter assembly and because it may make it difficult to locate all of the shutter blades at or very close to the desired optical point such as at a focus point along the light path. In many designs the motors used for operating the shutters have been mounted for movement in the assembly and have been drivingly connected to the shutters by complicated and expensive mechanisms. A disadvantage of movably mounted motors is the need to route electrical cabling to the moving motors. There is a long standing need for a simple, inexpensive, reliable and compact framing shutter assembly for a luminaire.
U.S. Pat. No. 6,550,939 discloses a shutter apparatus of a complex design that is expensive to make and assemble. It has a number of individual shutter assemblies, each including a shutter blade that is moved by a system of shutter blade drive motors and linear driving members. In addition, a further motor is used to rotate the entire shutter system including the shutter blade drive motors and linear driving members.